Respect sysconfdir for configuration file location

The sysconfdir is used if it exists, otherwise it fallbacks
to the previous default /etc.

cmdline/snapraid.c

@@ -241,7 +241,13 @@ void config(char* conf, size_t conf_size, const char* argv0)
 #else
 	(void)argv0;
 
-	pathcpy(conf, conf_size, "/etc/" PACKAGE ".conf");
+#ifdef SYSCONFDIR
+	/* if it exists, give precedence at sysconfdir, usually /usr/local/etc */
+	if (access(SYSCONFDIR "/" PACKAGE ".conf", F_OK) == 0)
+		pathcpy(conf, conf_size, SYSCONFDIR "/" PACKAGE ".conf");
+	else /* otherwise fallback to plain /etc */
+#endif
+		pathcpy(conf, conf_size, "/etc/" PACKAGE ".conf");
 #endif
 }
 

configure.ac

@@ -364,6 +364,12 @@ AC_ARG_VAR([TESTENV_SSSE3], [Test environment for SSSE3])
 AC_ARG_VAR([TESTENV_SSE42], [Test environment for SSE42])
 AC_ARG_VAR([TESTENV_AVX2], [Test environment for AVX2])
 
+dnl Expand default prefix, required to expand sysconfdir=$prefix/etc
+test "x$prefix" = xNONE && prefix=$ac_default_prefix
+
+dnl Set the configuration directory in config.h
+AC_DEFINE_UNQUOTED([SYSCONFDIR],["$(eval echo $sysconfdir)"],[Configuration directory])
+
 AC_CONFIG_FILES([Makefile])
 AC_OUTPUT
 

snapraid.1

@@ -996,9 +996,11 @@ files using a different hash.
 SnapRAID provides the following options:
 .TP
 .B \-c, \-\-conf CONFIG
-Selects the configuration file. If not specified it\'s assumed
-the file \[dq]/etc/snapraid.conf\[dq] in Unix, and \[dq]snapraid.conf\[dq] in
-the current directory in Windows.
+Selects the configuration file to use. If not specified in Unix
+it\'s used the file \[dq]/usr/local/etc/snapraid.conf\[dq] if it exists,
+or \[dq]/etc/snapraid.conf\[dq] otherwise.
+In Windows it\'s used the file \[dq]snapraid.conf\[dq] in the same
+directory of \[dq]snapraid.exe\[dq].
 .TP
 .B \-f, \-\-filter PATTERN
 Filters the files to process in \[dq]check\[dq] and \[dq]fix\[dq].
@@ -1231,8 +1233,10 @@ Prints the program version.
 SnapRAID requires a configuration file to know where your disk array
 is located, and where storing the parity information.
 .PP
-This configuration file is located in /etc/snapraid.conf in Unix or
-in the execution directory in Windows.
+In Unix it\'s used the file \[dq]/usr/local/etc/snapraid.conf\[dq] if it exists,
+or \[dq]/etc/snapraid.conf\[dq] otherwise.
+In Windows it\'s used the file \[dq]snapraid.conf\[dq] in the same
+directory of \[dq]snapraid.exe\[dq].
 .PP
 It should contain the following options (case sensitive):
 .SS parity FILE [,FILE] ... 

snapraid.d

@@ -694,9 +694,11 @@ Options
 	SnapRAID provides the following options:
 
 	-c, --conf CONFIG
-		Selects the configuration file. If not specified it's assumed
-		the file "/etc/snapraid.conf" in Unix, and "snapraid.conf" in
-		the current directory in Windows.
+		Selects the configuration file to use. If not specified in Unix
+		it's used the file "/usr/local/etc/snapraid.conf" if it exists,
+		or "/etc/snapraid.conf" otherwise.
+		In Windows it's used the file "snapraid.conf" in the same
+		directory of "snapraid.exe".
 
 	-f, --filter PATTERN
 		Filters the files to process in "check" and "fix".
@@ -930,8 +932,10 @@ Configuration
 	SnapRAID requires a configuration file to know where your disk array
 	is located, and where storing the parity information.
 
-	This configuration file is located in /etc/snapraid.conf in Unix or
-	in the execution directory in Windows.
+	In Unix it's used the file "/usr/local/etc/snapraid.conf" if it exists,
+	or "/etc/snapraid.conf" otherwise.
+	In Windows it's used the file "snapraid.conf" in the same
+	directory of "snapraid.exe".
 
 	It should contain the following options (case sensitive):
 

snapraid.txt

@@ -755,9 +755,11 @@ files using a different hash.
 SnapRAID provides the following options:
 
     -c, --conf CONFIG
-        Selects the configuration file. If not specified it's assumed
-        the file "/etc/snapraid.conf" in Unix, and "snapraid.conf" in
-        the current directory in Windows.
+        Selects the configuration file to use. If not specified in Unix
+        it's used the file "/usr/local/etc/snapraid.conf" if it exists,
+        or "/etc/snapraid.conf" otherwise.
+        In Windows it's used the file "snapraid.conf" in the same
+        directory of "snapraid.exe".
 
     -f, --filter PATTERN
         Filters the files to process in "check" and "fix".
@@ -994,8 +996,10 @@ SnapRAID provides the following options:
 SnapRAID requires a configuration file to know where your disk array
 is located, and where storing the parity information.
 
-This configuration file is located in /etc/snapraid.conf in Unix or
-in the execution directory in Windows.
+In Unix it's used the file "/usr/local/etc/snapraid.conf" if it exists,
+or "/etc/snapraid.conf" otherwise.
+In Windows it's used the file "snapraid.conf" in the same
+directory of "snapraid.exe".
 
 It should contain the following options (case sensitive):